This invention relates to underground power (especially high voltage power lines), telecommunication, cable television, fiber optic lines and the like and, in particular, to a shield used to expose such underground lines without damage to the lines or injury to the workers and the method of utilizing the shield to expose the underground lines.
Underground high voltage power lines, telecommunication lines (e.g. telephone lines), cable television lines, fiber optic lines and the like are normally housed within conventional standard size plastic conduits (e.g. pvc conduits) and sections of these conduits must be removed from about the lines to expose the lines prior to working on the lines. These underground power lines (especially high voltage power lines), telecommunication lines, cable television lines, fiber optic lines and the like, generally, must be replaced, when the insulation sheath about the wiring or optic fibers within the lines becomes cut or otherwise damaged, to avert a premature line failure while the line is placed in service. The replacement of these lines can be quite costly in time, labor and materials, especially for the replacement of high voltage power lines and fiber optic lines which are expensive. Thus, it is important to avoid damage to these lines when a conduit section is being removed from about the lines to expose the lines so that the lines can be worked on.
It is also very important to avoid injury to the workers through electrical shock, especially, when working with high voltage power lines. Frequently, when a section of conduit is being removed from about a line to expose the line within the conduit, the workers do not know whether or not the electrical power to the line has been shut off. In some cases, with multiple underground lines, the only way to absolutely determine whether or not the electrical power to the line has been shut off is to spike the line after the line has been exposed. Thus, while the workers are uncertain whether or not they are dealing with a live line, it is important to shield the workers from electrical shock to prevent injury to the workers.
By way of example, during the construction of shopping malls, industrial complexes, commercial buildings, and similar relatively large building projects, new or existing, buried or underground high voltage power lines or electrical cables have to be tapped into, spliced or otherwise worked on to provide electrical services to the project. Typically, there will be several different tubular conduits closely grouped together, within a trench, that each contain a different high voltage power line or electrical cable. Before one of these high voltage underground power lines can be tapped into, spliced or otherwise worked on, a length of one of the power lines to be tapped, spliced or otherwise worked on must be exposed by removing a section of one of the tubular conduits from about the power line. Due in part to the confined space within which the work must be performed and the presence of other power line containing conduits closely positioned about the conduit containing the power line to be worked on, the task of removing a portion or section of the conduit housing the power line to be worked on can be quite difficult to perform, especially without damaging the power line within the conduit or exposing the workers to possible electrical shock as the section of conduit is being cut away. As mentioned above, any damage to the insulation sheath of the high voltage power line or electrical cable within the conduit while removing the section of conduit may necessitate the replacement of a great length or portion of the high voltage power line. The cost for the replacement of one of these costly high voltage power lines, plus the added time and labor costs required to replace such a high voltage power line, can greatly increase the cost of tapping into, splicing or otherwise working on a high voltage power line. Thus, it is most beneficial to avoid damage to a high voltage power line when the conduit housing a high voltage power line is being cut away to expose the high voltage power line for both cost and safety reasons.
Once a high voltage power line has been exposed, the power line is checked to determine if the electrical power to the power line has actually been turned off prior to working with the power line. Otherwise, if the electrical power to the power line has not been turned off, anyone working with the power line would most likely be seriously injured if not killed. Typically, the power line is tested to determine if the electrical power to the power line has been turned off by spiking the power line with a spiking clamp (such as, a spiking clamp made by Hastings of Hastings, Michigan). The spiking clamp has a threaded spike with a pointed end that is used to penetrate the insulating casing of the power line and make contact with the wiring within insulating casing of the power line. The threaded spike is grounded and an eye on the second end of the threaded spike is turned with a shotgun stick (such as, a shotgun stick sold by Hastings of Hastings, Michigan) to cause the spike to penetrate the insulating casing and make contact with the wiring within the insulating casing. If the power line is hot (the electrical power to the power line has not been turned off) the contact of the spike of the spiking clamp with the wiring of the power line normally causes an eruption of hot flame from the power line at the location of the spike.